DE2244219A1 - REINFORCEMENT ELEMENT AND FITTINGS FOR A CONTAINER EQUIPPED WITH FLEXIBLE WALLS - Google Patents

Description

PATENT AGENT 5ÜR0 THOMSEN - TlEDTKE - BüHLING

TEL. (0811) 53 0211
63 0212 TELEX: S-24 303 topat N W Ä L T E PATENTA Frankfurt / M .: Munich: Dipl. Ing. W. Wtlnkauff Dipl.-Chem. Dr. D. Thomsen {Fox Hollow 71) Dipl.-ing. H. Tiedtke Dipl.-Chem. Q. Bühling Dipl.-Ing. R. Kinne Dipl.-Chem. Dr. U. Eggers

8000 Munich 2

Kalser-Ludwig-Platz 6 September 8, 1972

Uniroyal, Inc.
New York / USA

Reinforcement element and armature for a container equipped with flexible walls

The invention relates to unbreakable rigid fittings for liquid containers equipped with flexible walls, especially fuel tanks (often simple Called "fuel cells") for aircraft such as airplanes and helicopter containers that usually survive falls without damage. Catastrophic damage on aircraft fuel tanks usually result from "ripping" of those usually made of metal Fittings from the wall of the flexible container.

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This damage or crack causes the land to be flooded with fuel, making it an extremely dangerous condition leads.

As far as the armature constructions developed before the invention have an increased resistance to the Provide "pull out", they are expensive to install and not replaceable if they should be damaged in use. A requirement of the current military regulation for plug-in fuel tanks calls for that the water-filled fuel tank can withstand a fall from a height of 19.88 m (65 feet) onto a non-yielding surface without cracking. A crack, including damage on or in the vicinity of the valve, which results in leakage, represents a defect to fulfill this provision. Fuel tanks with fittings constructed in accordance with the invention consist of these Test without difficulty.

The invention resides in a novel base which is suitable for reinforcing the wall of a liquid container equipped with flexible walls in the area surrounding the fitting. Furthermore, the invention is based on a novel valve construction for one such container and on a liquid container equipped with flexible walls, which has such a fitting construction.

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The invention comprises a plurality of closely spaced, substantially concentric annular loops, for example rings or other shapes with parallel circumferences Strands of substantially stretch-resistant reinforcing material, preferably a glass fiber strand, wherein these novel supports are usually arranged in surfaces that are essentially parallel to the surrounding container wall are. Where the wall is bent at the point where the fitting is inserted, as well as where the fitting is in a corner of the tank, disposed in a cylindrical portion of the tank or in a portion with a composite curvature the reinforcing pads are curved accordingly so that they follow the contours of the tank wall in the surrounding area of the Adjust the fitting.

The preferred embodiment of the invention consists in using ready-made supports, which are made in advance separately from ring-shaped sheets of uncured, "However, hardenable polymeric material are made, with this being a spiral wound as an intermediate layer Have a layer of such a reinforcing material, which begins at the inner edge of the opening and spirals outwards to the outer edge of the pad.

The spiral winding is preferably designed in such a way that actual physical contact between one another

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other turns for at least 80 % of the spiral length. This minimum level of actual physical contact should exist for at least 80% of the spiral length of each individual turn.

While the documents preferably produced and used according to the invention are considered to be spiral-shaped Were described wound, the novel base according to the invention can also consist of a number of concentric Loops, like circular rings, can be made from a reinforcing strand, although not an economical one at the moment Way of producing such a precisely concentric strand support is known. Because it's a lot easier and if it is more practical to spirally wrap the strand, spirally wound supports are preferred. Of the slight theoretical advantage of a precisely concentric strand support is not large enough to accommodate the much higher Justify the cost and difficulty of making them. As used herein, "essentially concentric annular loops "includes both spirally wound loops from a reinforcing Strand as well as concentric individual loops from such a strand.

It should be noted that the invention is not limited to circular fittings, but in the same way can be applied to non-circular fittings.

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For example, it can be on oval, elliptical, square or right-angled fittings or on fittings with any other geometric shape. For such fittings, spiral winding is easy at least generally concentric with the fitting. Furthermore, the invention can be applied to all types of fittings. such as filling fittings, pouring fittings, fittings for access openings, etc. are used.

The invention is explained in more detail below using an exemplary embodiment with reference to schematic drawings.

Fig. 1 shows a top view of a typical spirally wound circular in accordance with the present invention manufactured underlay with the upper rubber layer partially removed;

Fig. 2 shows a section along the line 2-2 in Fig. 1, for a greatly enlarged representation of details; and

Fig. 3 shows a vertical section through a wall of a fuel tank with a circular side opening fitting, which according to the invention is appropriate.

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In FIGS. 1 and 2, the reference number 1 designates a reinforcing pad made according to the invention. This pad is typically made as follows. A layer 2 of Oummimaterial (unvulcanized, but vulcanizable fuel-resistant Qummi, mixed with conventional vulcanizing substances, but without reinforcing filler such as carbon black) with a thickness of about 0.025 inch an inside diameter a reasonable amount larger than the valve opening and an outside diameter gauge as calculated to support the wall load (stress) and the pad-wall shear stress. An Olasfiberstrang 3 or another suitable strand is spirally wound from the inner edge 4 of the central opening to the outer edge 5 of the base. The surface of the rubber layer 2 is coated with a suitable compatible Qummikleber shortly before or during winding; this adhesive layer is denoted by the reference number 6 in FIG. The spiral winding of the strand is carried out such that there is physical contact between adjacent windings of the strand for at least 80 % of the spiral length of each winding carried out. The same type of adhesive is applied to the upper side of the strand after completion of the winding and forms a layer, which is denoted by the reference number 7, list. The bonded arrangement obtained in this way is then used with

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a ring disk 8, which has the same inner and has external dimensions like the ring 2, but is considerably thinner - with a typical thickness of 0.02o3cm (0.008 inch) - with layer 8 of the same Rubber material as the layer 2 is made. After diffusion of the solvent from the adhesive layers, the base 1 is ready for use for a fitting installation.

In Fig. 3 is a typical fuel tank wall Io is shown, which is formed by three layers 11 of a rubberized fabric drawn onto a cardboard form 12 (the cardboard form is dismantled after vulcanization and removed). The wall Io is around the opening for that Armature by adding additional layers 13 and 14 made of conventional rubberized reinforcement fabric, which is reinforced by the conventional, rubberized, square woven The fabric from which the layers 11 are normally made are cut to the appropriate size and shape will. The details of the side door and its installation as shown in Figure 3 are conventional but will now described for the sake of completeness. A bolt 15 running through the mold 12 cooperates with a "plug" 16. to hold the valve in place until the container has finished vulcanizing. The fitting itself has an inner metallic member 17 with a round flange extending radially outward 2o and an axially extending portion 21, an outer one

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metallic member 22 which cooperates with the flange 2o in order to seal the stratification of the intermediate adjacent wall layers in a liquid-impermeable manner. The sealing effect is the result of vulcanization of the wall to the metallic members 17 and 22 by means of inlaid rubber material layers 3o, 31 and 32. The side door is engaged with the portion 21 of the inner link 17 by means of bolts 24 which are screwable are held in their position in a liquid-tight manner, as shown in FIG. 3. Conventional fittings details of this type, such as a wedge insert 25, an expansion seal 26 and a polypropylene spacer 27 not to be described in every detail. A conventional release liner, such as a nylon liner, is used to facilitate detachment of the mold 12 from the inside of the container.

In the typical application of the invention, as shown in Fig. 3, four such pads 1 are used alternately in combination with parts of wall layers 11, which represent extensions of the rubberized fabric from which the wall layers are formed. The resulting stratification of layers 11 and substrates 1 is held in a liquid-tight manner between the metallic members 17 and 22 with their inwardly extending sections. Typically, documents 13 and I ¹ * are off

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Ordinary rubberized, square woven wall fabric arranged on the sides of this layer and vulcanized to this, as shown in FIG. Layers of rubber material are preferably used as a support for achieving the liquid-tightness type described above on the surfaces of the radially outwardly extending channel-forming portions of the flanges 2o and 22 and provided on the radially innermost portion of the channel, i.e. around the outside of the axial member 21. These with the reference numerals 3o, 31 and 32 provided layers of rubber material are used to a dense cementing of the stratification with the metal parts 17 and 22 during the vulcanization of the container. The spirally wound pad according to the invention effectively allows the wall of the fuel tank, i.e. that enclosed between the metal elements of the armature Section to enlarge or change its shape, thereby allowing the wall to expand its direction during the passage of the first pressure wave Impact and continue for a limited, albeit small, period of time after impact and liquid-tight to stay. In this way, despite the force of the forces exerted during a fall, the fuel tank remains intact preserved in the area of the metallic armature.

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Although the splatter of the metal parts of the fitting, which surrounds the layering of wall layers and pads enclose the opening in the fuel tank wall in a liquid-tight manner, are shown in Fig. 3 at an angle to the actual tank wall (i.e. the flange surfaces in contact with the layering surfaces are beveled), they could just as well run parallel to the tank wall, by the thickness of the entire fitting area to reduce.

The reinforcing material used to manufacture the reinforcing pads according to the invention is almost without exception a strand of the type which is typical for tires, belts, etc. _{in the manufacture of reinforced rubber articles 1.} This strand generally contains fibrous or filamentary material which is twisted into a strand shape. Multiple individual strands of such material can be formed into a single larger strand using known strand forming techniques. Such a larger strand, like original individual strands, can serve as a reinforcing element for the production of the novel supports according to the invention.

The strand used in practicing the invention should be substantially non-extensible. Examples of im essential inextensible usable strand elements are those that are used to shape the inextensible tension elements in wedge

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belts and non-slip toothed belts are used, and those used to make belt inserts for tires. The fibrous used to make such strands or filamentary material can be of natural origin, for example Cotton or linen, or artificial, for example glass, rayon or polyester, or made of Metal, such as steel, exist, and this material can be in the form of a fiber web or a single thread.

The strands used in practicing the invention can be impregnated and "slurried" with subsequent drying in a known manner, for example with a so-called "RFL" (resorcinol-formaldehyde resin and rubber latex) solution or another solution which improves the adhesion of the strand to the rubber. In the same way, the rubber used in connection with the novel reinforcing element according to the invention can if necessary with certain known, solid chemical vulcanizing admixtures such as resorcinol donors or methyl donors be mixed. The strand should have low extensibility, high strength and high modulus. The selection of a suitable strand is well within the range of ordinary skill in the art. Appropriate Professionals can easily pick a strand of the has required properties in terms of strength, ductility, flexibility, etc. for a specific application. In general it can be said that the use of

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Strands of lower strength and higher extensibility makes the use of a larger number of supports for a given fitting necessary , and this is of course because of the greater weight and volume undesirable.

At present, fiberglass strand is preferred for practicing the invention. Such a strand can, for example of raw fiberglass having a tensile strength of 35200 kg / cm (500,000 pounds per square inch) and a modulus of elasticity of 0.738 χ Io kg / cm (lo, 5 χ Io engl. Pound per engl. Square inches). An example of a fiber optic strand, which experience has shown to be very which is well suited for use in the reinforcing element according to the invention is one made from such a fiber is made and in specialist circles alSjj ^ O - 75 5/5 (no Trade mark) - Qlasfiber tire cord is known and has the following properties:

Diameter o.122 cm to o.135 cm

(0.048 "to o, o53" inch)

Elongation at break 3 to 3.5 ί

Tensile strength at break 86.2 to 99 * 8 kg

(190 to 220 pounds)

Twist per cm o.6l

(Twist per inch) 1.55

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Other types of reinforcing cord can be used in place of fiberglass cord. An example is a steel cord that is made by twisting fine steel wires into a strand; at a Steel cord, the thickness would generally be somewhat less than that of a glass fiber cord; well known techniques such as Measurement of the wire can be used to achieve good putty with the rubber.

Results of full-size drop tests

Thirteen full-size drop tests were carried out on fuel filled with 518.7 liters (136.5 US gallons) of water cells carried out from a height of 19.76 m (65 feet) on an unyielding surface, their sequence and results are shown in the following table:

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Fitting
Type Number of from
thrown
fuel
cells Arrangement of
Fitting Result "Fiber Lok" 2 Side and bottom
the cell Wall damage
at the ar
matur and arma
turbo damage Il N 2 Side of the cell Wall damage
on the fitting • 1 Il 2 Side of the cell Wall damage
on the fitting • 1 Il 3 Side of the cell Wall damage
on the fitting Il Il 3 Faucet from the
Side removed
and at the top
side arranged Drop test
passed invention 1
1 . Side of the cell Drop test
passed

The valve used in last drop test in the above table, which passed the test after nine consecutive failed attempts with the "Fiber Lok" design was, according to the invention made with spirally wound ^ ⁵ O 75 5/5-Qlasfiberreifenstrang documents. Such a fitting enables the wall load to be borne more by the surroundings of the fitting than to end at the fitting edge. In the invention, the wall is only physically attached to the fitting by cementing and can therefore expand freely during the action of the dynamic pressure wave; the wall load is reduced by putty

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tension is transferred to a series of spirally wound pads and is thus transferred to the area around the fitting .

After performing the tests listed in the table above, thirteen additional fuel cells were used of the above type with spirally wound backings according to the invention were subjected to the test. Lots of these additional cells had nine fittings installed according to the invention. All of these cells passed the test with the exception of two, which were only damaged because the fittings were fitted with caps of a new type exhibited; this problem, which had nothing to do with the invention, was quickly exacerbated the .head thickness of the caps loosened.

The pad reinforcement according to the invention avoids rigid attachment of the fuel tank wall to the outermost one Edge of the armature, because the first wall tensions during the pressure phase when the cell impacts in the direction of the jacket develop. During this time the meridional wall stresses are negative.

As the pressure wave reaches its effect vertically through the barrier-free cell wall, a jacket tension is created harmonious with the wall load. In previously known constructions, an obstacle in the cell wall limits | s «B.

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Fittings and the like) * that has a reduced expansion capacity, the freely expanding wave front, resulting in a multiplication of the wall tension and eventual damage at the point of greatest stress differential. This does not happen with fittings according to the invention.

Previously known designs are just inadequate when using the smaller fittings, ie with those up to a diameter of about 0.16 to 12.7o cm (1-5 inches), and completely inadequate when using larger fittings than this case the invention, however, seems there is no practical limit to the size of the fitting; this is a great advantage as it enables very large fittings to be installed without the risk of failure.

In addition to the exceptional advantage of being able to easily pass the fuel tank Capable of rigorous drop testing, the invention also significantly reduces manufacturing time. The valve according to the invention is inexpensive to manufacture and requires very little assembly work. On the other hand, the processing of the "Fib Lok" fitting is very tedious and results in high labor costs The valve type is also very costly to produce because of the large number of circumferential holes and the demanding post-treatment requirements.

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The ease with which fittings according to the invention can be replaced if they become through use or misuse should be damaged during manufacture or in use is the most conspicuous and significant Advantage of the invention. It is easy to find a damaged or defective fitting installed according to the invention is to expand and install a replacement for it. Such an expansion can be achieved by loosening the metal fittings done by layering and pulling out. New 'metal parts are installed as needed, one being self-vulcanizing Rubber glue for cementing the layers to the walls of the channel formed by the new metal pieces is used. In this way, an expensive gasoline tank that would otherwise have to be thrown away can be used at a low cost be repaired. This advantage of easy interchangeability of fittings manufactured according to the invention cannot be achieved with the "Fiber Lok" type of fitting, because in the latter, the fan-like bundles of reinforcing Strands cannot be removed and replaced with anything that achieves the necessary accuracy.

Another notable advantage of the invention arises from the fact that the number of documents a function of the wall tension or the impact-related wall

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load as a result of an impact. With the "Fiber Lok" type of fitting, only a maximum number of strings can be used, and if the wall load exceeds the string loading capacity If it exceeds, a failure occurs and there is no way to achieve a greater wall strength of the fitting. In the invention, it is only necessary to achieve a greater armature wall strength, more of the to add novel documents according to the invention.

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Claims (6)

Claims 1. Fitting for an opening in a wall of a liquid container equipped with flexible walls, characterized by reinforcing pads (1) in the wall (lo) surrounding the opening, these pads (1) in the substantially concentric annular turns of substantially have stretch-resistant reinforcing material (3) which are arranged around the opening. 2. Fitting according to claim 1, characterized in that the reinforcing material made of textile, metal or glass fiber strand consists. 3. Fitting according to claim 1 or 2, characterized in that the reinforcing material spirals around the opening is wound. l |. Fitting according to claim 1 or 2, characterized by physical contact between adjacent turns of the reinforcement material for at least 80 percent the spiral length. 5. Fitting according to one of the preceding claims, characterized in that the material around the opening in Planes are arranged that are generally parallel to the plane of the adjacent container wall » 30981 1/0882 22U219 6. Fitting according to claim 5 »characterized in that the elements of the documents (1) by a hardened, fuel-resistant, polymeric material, which is compatible with the fuel-resistant polymeric material used in the container wall, are cemented together to form a layer. 30981 1/0882